Underfeed stoker



JUL 19, 1932. w c oss 1,842,359 V UNDERFEED STOKER Filed Nov. s, 1928 2 Sheets-Sheet 1 INVENT OR WallerM Cmss 1 9, 1932. I 4 w c oss 1,842,359

UNDERFEED STOKER Filed Nov. 8,1928 2 Sheets-Sheet 2 I I I I ill] IN V EN TOR.

Waite/M Cross 4 Hal ATTORNE I Patented Jan. 19, 1932 p um'rso STATES rivrslslT orrlca WALTER I. GROSS, OI IAIBABOITY, MISSOURI; ANNE H. CROSS, EXEGUTBIX OF SAID '-WAII1ER I. 03088, DECEASED, ASSIGNOR '10 CROSS COAL-O-MATIC COMPANY, OF KANSAS CITY, MISSOURI, A CORPORATION OF MISSOURI UNDEBFEED STOKER Application filed November 8, 1928. Serial No. 318,022.

7 This invention relates to improvements in an automatic underfeed stoker, and refers more particularly to a draft control by means of which a portion of the air draft supplied '5 to the main combustion retortis diverted and distributed around the space surrounding the retort to assist in completely consuming thefuel after it has passed the li a or circumference of the retort. This aux iary draft is'preferably taken from the mam air draft duct through a controlled damper arrangement so that the pressure on the space or grates surrounding the main retort will be a differential and lower pressure than the pressure of the air supplied to the combustion retort through the main air draft duct. Fig. 1 is a side view, partly in elevation and partly in section, of the stoker installation. I

Fig. 2 is a .view taken along the line 2-2 in Fig. 1. p I

Fig. 3 is a view taken along the line 3-3 in Fig. 1. V V

Fig.4 is a view taken along the line 4.-4

. '25 in Fig. 3.

Fig. 5 is an enlarged .detail of the removable and adjustable grates surrounding the combustion retort.

Referring to the drawings, at 1 is shown 8 diagrammaticallythe masonry portion of a furnace installation upon which is mounted a boiler 2 having flues 3, and a combustion space 4..

Mounted in the furnace and below the combustion space of the boiler is positioned the combustion retort 5. The combustion retort consists of a fuel pot 6 surrounded by an air duct or jacket 7. In the throat of the fuel pot are slotted tiles 8. The slots or tuyeres 9 communicate with the air duct 7 so that air supplied from the blower orfan 10 through the duct 11 and jacketed pipe 12 to the air duct 7 surrounding the fire pot is introduced into the bed of coal through the tuyere's 9 in the throat of the fire pot. The fuel is supplied from a hopper 13 by means ofa screw conveyor let'rotated by means of v the motor 15 which drives both the fan and the screw conveyor. by suitable gears and driving connections enclosed within the easing 16 and forming no part of the present invention. This fuel, which is preferably coal, is fed from the hopper by means of the screw 14 through the fuel pipe 17 communicating between the hopper and the combustion pot as or retort.

Surrounding the retort are positioned a set of grates 18 which are removable and adustab e. The lower, flat horizontal portion, designated 18, of the grate, is supported ufpon a shoulder or wall such as that shown at 19 in Fig. 3, and upon the edge of the combustion retort. A vertical portion 18 and thenpper horizontal portion 18 form a hollowe out space beneath each one of the grates. A second vertical portion 18 is slotted at 20 so that the auxiliary air introduced below the grates flows through the hollow portion of the grates and out into the bed of coal or fuel through the ducts 20 in the we direction shown by the arrows inFig. 5.

The supporting grates 18 are adjustable, that is, they may be pushed together or ex tended as long as there is an opening or hollow portion formed beneaththe grates to per- 15 mit the passage of air through the slots 20.

Also they may be easily removed or replaced as they are setwithout fastening on supports to cover the ash pit space surrounding the combustion retort.

To supply this auxiliary air to the tuyere grates 18 surrounding the combustion retort, a closure or damper 21 is. hinged to the air jacket 7 of the retort. This closure or dam er covers an opening or port and is 'adjusta le by means of a manually controlled damper rod 22. This closure serves to control'thez auxiliary air supplied beneath the tuyere 1 grates 18 and regulates the differential air draft or air pressure of the induced air sup- 9 plied as draft to both the combustion retort and the tuyere' grates surrounding the combustion retort. v

In the burning of bituminous coal, it is possible by this construction to vary the pressure in the tuyeres 9 and supply at the same time a differential lower pressure to the tuyere grates 18 surrounding the combustion retort of the Stoker, thus making it possible to effect a more complete and efficient burning 100 of the coal in the combustion retort and the tuyere grates respectively. According to the volatile constituents present in the coal to be burned, it will be necessary to regulate the 5 amount of air supplied to the retort and to the tuyere grates. Also to achieve smokeless combustion the difierential pressures beneath the retort and the tuyere grates may be governed by means of the damper or shutter 21 10 which permits a portion of the draft to escape into the ash pit'and rise through the tuyere grates to pass through the partially consumed 7 fuel bed supported on the tuyre grates. It, is desired to so-control the differential pressures in the retort and beneath the tuyere ates that the volatile hydrocarbons are exausted or burned from the fuel before it is crowded out of the retort onto the tuyere grates surrounding the retort. Thus the volatile hydrocarbons will be burned by the air discharged from the retort tuyeres 9 and the carbonaceous material primarily taken care of or burned while passing over the tuyere grates 18.

5 The ash pit of the boiler is sealed so that the pressure beneath the tuyei-e grates cannot escape except through the openings 20 in the grates themselves. No ashes are allowed to fall through the grates and the tuyeres or air passages extend horizontally through a vertical portion of the grates, thus preventingthe clogging of the air draft passageways by the accumulation of dirt and ashes.

I claim as my invention:

An underfeed stoker having in combination a combustion retort, a fuel supply duct, 9. fuel feeding means mounted in said duct, an air supply duct positioned around said fuel supply duct and said combustion retort whereby the air supply is heated to increase the thermodynamic efiiciency, air supply openings in said combustion retort, grates provided with air openings surrounding the combustion retort, an air chamber positioned around the air supply duct, said chamber being in communication with the combustion space by means of said grate opening :and a bleeder damper adapted to admit air into i said air chamber from the air duct, thereby permitting a reduction of the air supply to the combustion retort and admitting air-to the grate openings enabling a flexib e com bustion control without varying the air duct pressure, and allowing a complete combustion of the fuel which overflows the combustion retort to the ates.

. ALTER M. CROSS. 

